1. Field of the Invention
The present invention relates to an antenatal training device, and more particularly to a device which releases psychological and physiological stress and tension of a pregnant woman by stimulating her senses of hearing, and in turn induces the woman and her fetus to a mentally serene state during a gestation period.
2. Description of the Related Art
In general, all living individuals generate brain waves as kind of vital waves. Such brain waves represent different frequencies in accordance with an awakening state or a degree of a mental stability, and various devices employing this variation in frequency have been developed. Typically, a medical appliance for diagnosis and a lie detector utilizing a variation in brain wave frequency have already been put to practical use, and especially a device for promoting learning effects by creating a psychological serenity has also been developed.
Brain waves are accompanied with a sort of variation in voltage generated rhythmically from a brain part of a human body, which has frequencies of approximately 1 to 60 Hz and voltages of approximately 10 to 100 .mu.V. Such brain waves are divided into a .delta. (delta) wave, an .alpha. (alpha) wave, a .delta. (beta) wave in the lower order of a frequency band range. It has been found that the .alpha. (alpha) wave of frequencies of 7 to 11 Hz among various brain waves is generated in a condition of the human mind and body being under a stable, comfortable and relaxing state.
In U.S. Pat. No. 4,898,179, dated Feb. 6, 1990, entitled "Device for Detecting, Monitoring, Displaying and Recording of Material and Fetal Vital Signs and Permitting Communication between a Woman and Her Fetus," there is provided a device for detecting, monitoring, displaying and recording a representation of the heartbeats of a pregnant woman and her fetus. In this prior art device, signals representative of heartbeats and movements of the fetus detected can be recorded for later playback. Also, a microphone and speaker permit a woman to provide an audio stimulation to the fetus (or so called fetal child), and the fetal response to this stimulation can then be monitored.
However, the above-mentioned device allows the woman to provide an audio stimulation to the fetal child, and in particular, replies on only signals representing the heartbeats, thereby causing a failure in an antenatal training through mental and emotional stability of the pregnant woman's herself. Particularly, considering that mental and emotional stability of the pregnant woman is essential for psychological and emotional development of the fetus during a gestation period, the above-mentioned U.S. Patent has a relatively very limited aspect in view of a device for assisting in antenatal training.